(1) Field of the Invention
The present invention relates to an electromagnetic contactor including a fixed core engaged with a fixed insulating base and a bobbin of an electromagnetic coil, and a movable core which is actuated by the electromagnetic coil and can be attached to or detached from the fixed core, and particularly to an alternating-current electromagnetic contactor which reduces an impact generated when the fixed core and the movable core are attached to each other to improve mechanical endurance.
(2) Description of the Related Art
In a general electromagnetic contactor, a movable core and a fixed core are formed in an E-shape, and are arranged to face an end surface of each leg portion. In addition, by switching a state where the movable core and the fixed core are detached from each other by means of a metal spring or the like and a state where the movable core and the fixed core are attached to each other by means of the drawing force of an electromagnetic coil, a movable contact and a fixed contact become conductive or nonconductive and opening/closing of an electric circuit is controlled.
In order to enhance the durability of the movable core and the fixed core by reducing an impact generated when the movable core and the fixed core collide with each other in a conventional electromagnetic contactor, a buffer member made of an elastic material such as a metal spring is inserted and fitted into a through-hole formed in the thickness direction of the fixed core, and oscillation and collision noise generated when the both of the fixed and movable cores collide with each other are reduced with the buffer member, as described in Japanese Patent Application Laid-Open No. 2008-277010. In addition, a buffer member made of an elastic material such as rubber is arranged between the fixed core and a fixed insulating base to reduce oscillation and collision noise generated when the both cores collide with each other.
However, the buffer members in the above-described conventional technique reduce the oscillation after collision of the movable core and the fixed core, but do not reduce the collision velocity of the both of the movable and fixed cores. On the other hand, mechanical abrasion of contact surfaces of the both of the movable and fixed cores is largely affected by the collision velocity, and it has been necessary to decrease the collision velocity from the past. Further, an elastic material such as rubber may be used as a buffer member. However, a sufficient elasticity can not be obtained due to limitation in dimension of the electromagnetic contactor in the moving direction, thus resulting in a poor buffer effect when the both of the movable and fixed cores collide with each other.
In view of the disadvantages of the above-described conventional technique, the present invention is to provide an electromagnetic contactor in which the collision velocity of both of the movable core and the fixed core is effectively reduced to improve mechanical endurance of an electromagnet.